A semiconductor light-emitting device including a semiconductor light-emitting element is, as shown in FIG. 1, formed by the semiconductor light-emitting element 1, a molded resin 2, a bonding wire 3, a phosphor layer 4, a lead frame 5 and the like. A package includes mainly a conductive metal wiring such as the lead frame 5 and the insulating molded resin 2.
Conventionally, thermoplastic resins such as polyamides to which a white pigment is added has been generally used as insulating materials for molded resins (refer, for example, to Patent Document 1). Light-emitting efficiency of semiconductor light-emitting devices which are desired to have directionality of emitted light is improved not only by the light which is emitted in the desired direction from the semiconductor light-emitting element, but also by causing light emitted in other directions to be reflected by molded resins, metal wirings such as lead frames and reflecting materials into the desired direction. Thermoplastic resins such as polyamides are translucent. Therefore, when a molded resin is used for reflection, the resin is mixed with a white pigment, so that light generated from a semiconductor light-emitting element can be reflected due to the difference in refractive index between the resin and the white pigment and light-emitting efficiency of the semiconductor light-emitting device can be improved.
In the above Patent Document 1, because some white pigments have insufficient reflection efficiency, some light beams are absorbed or transmitted. As a result, light generated from a semiconductor light-emitting element cannot be concentrated in a desired direction, thereby sometimes decreasing efficiency of the semiconductor light-emitting device.
In addition, there is currently a trend toward higher reflow temperatures due to a strong trend toward the use of higher melting lead-free solders brought on by environmental concerns. Polyamides are thermoplastic resins, and polyamides are thus softened by this heat and the heat resistance of the package then becomes a problem in the case of packages that use polyamide. Furthermore, polyamides are subject to photodegradation and thermal degradation by ultraviolet radiation and heat, and degradation by light has become a problem in particular when light-emitting elements are used that have a light-emission range that extends into high-energy wavelength regions, such as the blue to near-ultraviolet semiconductor light-emitting elements whose commercialization has been ongoing in the recent years. Moreover, thermal degradation and photodegradation have become even more significant problems due to the heat and high luminous flux light generated by the semiconductor light-emitting element as a result of contemporary demands for brighter light-emitting elements.
Otherwise, an alumina-containing sintered ceramic may be used as the insulating material in those cases in which heat resistance is required (refer, for example, to Patent Document 2). A package that uses this ceramic does have a good heat resistance, but its production requires a high-temperature sintering step post-molding. These sintering steps have involved problems such that costs are high due to electricity costs and the like, and mass-productivity is low as defective products are likely to be produced due to changes in the size and shape of molded products in each sintering.
In contrast to the preceding, a case has also recently been introduced that is provided by molding a silicone resin composition that uses a polyorganosiloxane for the resin and uses titanium oxide for the white pigment (refer, for example, to Patent Document 3). The use of the polyorganosiloxane for the resin is intended to improve the heat resistance over that for the use of polyamide.    Patent Document 1: Japanese Patent Application Laid-open No. 2002-283498    Patent Document 2: Japanese Patent Application Laid-open No. 2004-288937    Patent Document 3: Japanese Patent Application Laid-open No. 2009-155415